Bimetal operated coolant level switch



Dec. 20, 1966 w. c. SHAW BIMETAL OPERATEDy COOLANT LEVEL SWITCH Filed Jan. 26, 1965 Maman *l \b/ INVENTOR, W/LLARD C. SHAW ATTORNEY United States Patent O 3 293,390 y BIMETAL OPERATED COOLANT LEVEL SWITCH Willard C. Shaw, Anderson, Ind., assignor to General Motors Corporation, Detroit, Mich., a corporation of Delaware Filed Jan. 26, 1965, Ser. No. 428,120 Claims. (Cl. 20D-113) This invention relates to electric switches and more particularly to a type of switch responsive to the temperature of huid in a cooling system of a vehicle engine.

It is an object of the present invention to provide an improved electric switch adapted to be inserted into a wall of the cooling system of a vehicle engine which is responsive to an overheat condition therein.

It is another object of the present invention to provide an improved electric switch for sensing an overheat condition in a cooling system of vehicle engine, said switch using a bimetallic element deflectable along its longitudinal axis.

It is still another object of the present invention to provide an improved electric switch for use in sensing an overheat condition in a cooling system of a vehicle engine which has a novel means for sealing the operative area of the switch body from the cooling system.

Further objects and advantages of the present invention will be apparent from the following description, reference being had to the accompanying drawings wherein a preferred embodiment of the present invention is clearly shown.

In the drawings:

FIGURE 1 is an elevational view of the subject invention shown in its operative environment;

FIGURE 2 is a sectional view of the subject invention, the switching mechanism shown in a conguration it would assume under normal temperatures in the cooling system;

FIGURE 3 is a sectional view taken along line 3-3 of FIGURE 2;

FIGURE 4 is a sectional View taken along line 4 4 of FIGURE 3;

FIGURE 5 is a sectional view of the subject invention, the switching portion shown in the configuration it would assume during an overheat condition in the cooling system.

Referring to FIGURE l, a temperature sensitive switch is illustrated as being inserted into a wall 12 of the cooling system of a vehicle engine, generally designated by the numeral 14. A battery 16 supplies power through an ignition switch 18 to a light 20 through lead 22 and to a terminal 24 of the switch 10 through a lead 26. The switch 10 is grounded directly to the wall 12 of the engine 14 as is the battery 16. The light 20 is grounded selectively in a manner to be hereinafter described through lead 28 and a terminal 30 of the switch 10.

Referring to FIGURE 2, the switch 10 includes a nonconductive portion 32 and a threaded conductive portion 34 adapted to be threaded into the wall 12. A conductive sleeve 36 engaging the terminal 24 is pressed into an aperture 38 in the non-conductive portion 32 of the switch body 10. A threaded conductive slug 40 is threaded into the sleeve 36 to a point in a switching compartment 42 wherein it can be conducti'vely engaged by a lirst contact 44. The contact 44 is carried by a conductive rivet 46 passing through a resilient member 48. The rivet 46 also engages a sinusoidal shaped bimetallic element 50.

An integrally formed raised portion or nipple 52 formed on the resilient element 48 is engageable with a resilient conductive strip 54 to drive said strip into engagement with a threaded slug 56 similar to the slug 40. The conductive strip 54, sometimes referred to herein as a second contact means, and the iirst contact means 44 are better seen in FIGURE 3 and FIGURE 4. The slug 56 is threaded into a sleeve S8 pressed into an aperture 60 of the non-conductive portion 32 in much the same manner as the sleeve 36 and the slug 40. The sleeve 58 conductively engages the terminal 30.

The bimetallic element Sil is attached on an opposite end from the end engaging the rivet 46 by a conductive element 62. An insulating member 63 is disposed between the major portion of the element 5() and the element 62. The element 62 conductively engages the conductive portion 34 of the switch body 10 that is grounded to the wall 12. An insulating ring 64, the element 62, the resilient element 48, the second contact means 54, and an insulating ring 66 are sandwiched in assembly of the subject switch between the non-conductive portion 32 and the conductive portion 34 by a crimped-over lip 68 engaging a pad 70 of the non-conductive portion 32 bearing against a wall 72 of the conductive portion 34.

It should be noted that a conductive path normally exists through the terminal 24 connected to the ybattery 16, to the sleeve 36, the slug 40, the first contact 44, through the bimetal 50, through the conductive element 62 to ground. Therefore, the bimetallic element 5G is normally heated and would deflect but for the cooling supplied it by a fluid 74 normally disposed in the cooling system of the vehicle. Therefore, the bimetallic element 5t) and the coolant 74 are at an equilibrium temperature in a predetermined range of temperatures, for example, 0 to 240 F., which is the normal acceptable range of temperat-ure in an engine cooling system. Another path for current flow potentially exists from the power source 16 and the light 20 to the terminal 30, the sleeve 58, and to the slug 56. The slug 56 is selectively grounded by movement of the second rcontact means 54 engaging the slug 56 in response to a deflection of the bimetallic element St). It should be noted that the switch is constructed so that the slug 56 is grounded directly through the second contact means 54 directly engaging the conductive portion 34 of the switch 10. Therefore, it is seen that the nipple 52 effectively advances the second contact means 54 ahead of the first contact means 44 while both contact means respond to movement of the resilient element 48 in a diaphragm-type manner engendered by the bimetallic element 50 during its deflection. It should be understood that resilient strip 44 is movable away from terminal 40 when the fluid 74 cools down sufficiently to contract the bimetal toward one extreme of movement.

In operation, referring to FIGURE 2, the configuration of parts herein typies the relative position of the components during the normal functioning of the subject switch. By normal functioning is meant an operating condition of the |cooling system of the vehicle wherein the coolant is Within predetermined temperature limits. During this normal condition of operation, the heating of the bimetal 50 through the circuit entering the switch at the terminal 24 is offset in that the heat generated in the ybimetal 50 is dissipated in the coolant or fluid 74. The bimetallic element 50 is thereby restrained and no deflection takes place thereby maintaining a spaced relationship between the second contact means 54 and the slug 56. It is therefore obvious that, during this condition of operation, the lamp 20 -cennected to the terminal 30 is not grounded and is therefore not energized.

Referring to FIGURE 5, it is seen that the coolant or uid 74 has receded to a point below the bimetallic element 50. During this condition of operation, the heat generated in the bimetallic element 50 is not dissipated into the fluid 74 and, therefore, is free to deflect. The sinusoidal shaped bimetallic element 50 is deflectable substantially along its longitudinal axis and, therefore, slides along the insulating member 63. As previously stated, the bimetallic element 50 directly engages the rivet 46, the

sealing resilient member 48, and the second Contact means 54 indirectly through the nipple 52. Therefore, as a deflection of the bimetallic element 50 takes place, the second contact means 54 is driven into conductive engagement With the slug 56. Ground for the lamp 20 through the terminal 30, the sleeve 58 and the slug 56 is therefore provided and the lamp 20 will become energized. It should be noted that the lamp 20 is preferably placed in the driving compartment of a vehicle wherein it is visible to the operator thereof.

The resilient element 48 can be of any elastomeric material that is an electric insulator and that is impervious to chemical substances normally found in cooling systems of vehicles. The element 48 also serves as a water seal between the cooling system of the vehicle and the compartment 42 wherein the switching action takes place. The combination of the linearly deectable bimetallic element 50 and the resilient member 48 engaging the contacts 44 and 54 make possible a water proof switch that is easily insertable into a cooling system of a vehicle at any desired point to provide an indication of an overheat condition therein. It should be noted that the bimetallic element 50 normally has its heat dissipated in the Huid 74. The bimetallic element 50 is preferably made responsive to a temperature of the fluid 74 above the normal desired operating temperature of the cooling system. It is clear that no fluid in the cooling system will have the same effect as an overheated fluid in that the heat from the element 50 will not be dissipated in either case.

While the embodiment of the present invention, as herein disclosed, constitutes a preferred form, it is to be understood that other forms might be adopted.

What is claimed is as follows:

1. A temperature sensitive switch comprising: a switch body having a threaded body adapted to be threaded into a wall of a fluid container; a first terminal carried by said switch body and adapted to conductively engage a lead to a power source; a second terminal carried by said switch body and adapted to conductively engage an indieating lamp; a bimetallic element carried by said switch body and having a portion arranged to be suspended into a fluid passage, said bimetallic element being deflectable substantially along its longitudinal axis in response to temperature changes of fluid in the fluid passage; first movable contact means carried by said bimetallic element and being drivable into engagement with said first terminal; second contact means carried by said switch body and being grounded therethrough; and resilient means engaging said bimetallic element insulating an area of said switch body in which the switching takes place and adapted to be driven by said bimetallic element during a deflection thereof in response to a temperature change of the fluid in the container into conductive engagement with the second terminal means, said first contact means being deflectable while engaging the first terminal means and deflecting during the time when said second contact means deflects into said second terminal.

2. A temperature sensitive switch comprising: a switch body having a threaded body adapted to be threaded into a wall of a fluid container having a fluid passage; a first terminal carried by said switch body and adapted to conductively engage a lead to a power source; a second terminal carried by said switch body and adapted to conductively engage an indicating lamp; a bimetallic element carried by said switch body and having a portion arranged to be suspended into the fluid passage, said bimetallic element being defiectable substantially along its longitudinal axis in response to temperature changes of fluid in the fluid passage; first movable contact means carried by said bimetallic element and being drivable into engagement with said first terminal; second contact means carried by said switch body and being grounded therethrough; and a resilient member stretched between opposed portions of the switch body and effectively isolating an area within the switch body in which the first and second terminals and first and second contact means are disposed from fluid in thecontainer, said resilient member having an integrally formed raised portion engaging said second contact means during a linear deflection of said bimetallic element thereby completing an electric circuit to the indicating lamp as the fluid in the container exceeds a temperature contained Within said predetermined limits.

3. The temperature sensitive switch according to claim Z wherein the bimetallic element is attached to the resilient member by a conductive rivet, said conductive rivet operatively carrying the first contact means.

4. The temperature sensitive switch according to claim 2 whereinthe bimetallic element has a cross section of multiple sinusoidal shape thereby being arranged to be deflectable substantially along the longitudinal axis of said bimetallic element.

5. A temperature sensitive switch according to claim 2 wherein the first contact means is a resilient arcuately shaped deflectable metallic strip carried by said resilient means and said second contact means is an arcuately shaped resilient strip carried by said switch body in a complementary manner with respe-ct to said first contacl means.

References Cited by the Examiner UNITED STATES PATENTS 1,991,495 2/ 1935 Derby. 2,077,294 4/ 1937 White. 2,759,066 8/ 1956 Short et al. 20D-138 3,081,393 3/1963 Wohl 200-138 X 3,221,125 11/1965 Young ZOO-138 BERNARD A. GILHEANY, Primary Examiner.

T. D. MAC BLAIN, Assistant Examiner. 

1. A TEMPERATURE SENSITIVE SWITCH COMPRISING: A SWITCH BODY HAVING A THREADED BODY ADAPTED TO BE THREADED INTO A WALL OF A FLUID CONTAINER; A FIRST TERMINAL CARRIED BY SAID SWITCH BODY AND ADAPTED TO CONDUCTIVELY ENGAGE A LEAD TO A POWER SOURCE; A SECOND TERMINAL CARRIED BY SAID SWITCH BODY AND ADAPTED TO CONDUCTIVELY ENGAGE AN INDICATING LAMP; A BIMETALLIC ELEMENT CARRIED BY SAID SWITH BODY AND HAVING A PORTION ARRANGED TO BE SUSPENDED INTO A FLUID PASSAGE, SAID BIMETALLIC ELEMENT BEING DEFLECTABLE SUBSTANTIALLY ALONG ITS LONGITUDINAL AXIS IN RESPONSE TO TEMPERATURE CHANGES OF FLUID IN THE FLUID PASSAGE; FIRST MOVABLE CONTACT MEANS CARRIED BY SAID BIMETALLIC ELEMENT AND BEING DRIVABLE INTO ENGAGEMENT WITH SAID FIRST TERMINAL; SECOND CONTACT MEANS CARRIED BY SAID SWITCH BODY AND BEING GROUNDED THERETHROUGH; AND RESILIENT MEANS ENGAGING SAID BIMETALLIC ELEMENT INSULATING AN AREA OF SAID SWITCH BODY IN WHICH THE SWITCHING TAKES PLACE AND ADAPTED TO BE DRIVEN 